Safety valve for a fluid extraction well installation

Abstract

The invention refers to a safety valve having a double seal system that combines a metal-metal seal and an elastomeric ring arranged on the valve body. The safety valve comprises and external casing having a hollow main body configured to receive a piston that slides axially between an upper position and a lower position, the safety valve comprises a closing element pivotally attached to an annular seat and actuated by a torsion spring, wherein said closing element has a support face on the annular seat comprising a recessed perimeter surface and sloping intermediate surface jointly forming a first seal region, said annular seat has a second seal region consisting with said first seal region on the closing element, both regions defining a metal-metal seal, and wherein said second seal region on the annular seat comprises a perimeter groove configured to house a seal element made from elastomer.

The invention claimed is: 
     
       1. A safety valve, comprising an external casing ( 1 ) that has a hollow main body, an upper end ( 2 ) and a lower end ( 3 ), said main body of said external casing ( 1 ) configured to receive a piston ( 12 ) with a piston end ( 4 ) that slides axially between an upper position and a lower position, on the upper end ( 2 ) of said external casing ( 1 ) arranging an upper connection element ( 5 ), while at the lower end ( 3 ) of said external casing ( 1 ) there is a closing element ( 6 ) pivotally attached to an annular seat ( 7 ) and actuated by a second actuator ( 14 ), said piston end ( 4 ) comprising, in the lower portion thereof, a shoulder ( 8 ) that together with the main body inner wall of the hollow external casing ( 1 ) and the upper connection element ( 5 ) define an annular space configured to house a first actuator ( 9 ), characterized in that said closing element ( 6 ) provides a support face ( 17 ) on the annular seat ( 7 ), said support face ( 17 ) having a central surface ( 18 ) that projects in the axial direction and a recessed perimeter surface ( 19 ), wherein the central surface ( 18 ) and the recessed perimeter surface ( 19 ) join without interruption through a sloping intermediate surface ( 20 ), the recessed perimeter surface ( 19 ) and sloping intermediate surface ( 20 ) jointly form a first seal region, and said annular seat ( 7 ) has a second seal region consistent with said first seal region on the closing element ( 6 ), both regions thus defining a metal-metal seal ( 15 ), and wherein on an outer perimeter edge ( 21 ) of the second seal region of the annular seat ( 7 ), there is a perimeter groove ( 16 ) configured to house a seal element ( 13 ). 
     
     
       2. The safety valve according to  claim 1 , characterized in that said upper connection element ( 5 ) has an interface for the installation and removal of the safety valve. 
     
     
       3. The safety valve according to  claim 1 , characterized in that said closing element ( 6 ) is a clapper joined to said annular seat ( 7 ) by means of a hinged joint. 
     
     
       4. The safety valve according to  claim 1 , characterized in that a ledge ( 10 ) forms a lower stop for the stroke of said piston end ( 4 ). 
     
     
       5. The safety valve according to  claim 1 , characterized in that a ledge ( 10 ) defines a calibrated passage ( 11 ) for the stroke of piston ( 12 ). 
     
     
       6. The safety valve according to  claim 1 , characterized in that said second actuator ( 14 ) is a torsion spring. 
     
     
       7. The safety valve according to  claim 6 , characterized in that said hinged joint has a rotation axis where said torsion spring ( 14 ) is inserted. 
     
     
       8. The safety valve according to  claim 1 , characterized in that said central surface ( 18 ) and said sloping intermediate surface ( 20 ) define a frustoconical cross-section. 
     
     
       9. The safety valve according to  claim 1 , characterized in that said seal element ( 13 ) is of elastomeric type. 
     
     
       10. The safety valve according to  claim 9 , characterized in that said seal element ( 13 ) is composed of highly abrasion-resistant elastomers, such as nitrile butaidene rubber (NBR), ethylene propylene diene elastomer (EPDM), hexafluoropropylene thermopolymer, with vinylidene fluoride, tetrafluoroethylene and perfluoromethyl vinyl ether (FPM), elastomeric polyurethane, elastomeric silicone (VMQ, PMQ, PVMQ).